This invention relates to the field of water purification, and particularly to the removal of surface contamination, especially in the form of oil in thin films known as "rainbows", from moving bodies of water, the movement being either natural, as in streams and canals, or artificial, as induced by pumping for example.
It is notoriously well known that oil spills occur and are not only expensive in the loss of the oil but many times as expensive in the cost of clean up operations. It is also well known that a little oil as a contaminant goes a long way in covering the surface of water, and that the resulting thin film spreads rapidly and is difficult to remove. The injurious effects of oil spills on the ecology of the environment are currently well popularized.
There has been much activity in the field of containing oil spills and removing the contaminating oil. In general many methods and arrangements for removing oil are successful when the quantity of oil present is relatively large, but they fail when the quantity of oil is so small as to comprise no more than an extremely thin surface layer detectable principally by its optical properties which produce the familiar "rainbow" surface on otherwise clear water. The word "rainbows" will be used herein to refer to layers of oil of this slight thickness, which incidentally always remain even after the other known methods and arrangements have been practiced to completion.
The invention constitutes a carrying forward of and an improvement in the invention disclosed in my copending application jointly with Edward C. Straub, Ser. No. 408,860, filed Oct. 22, 1973 (now U.S. Pat. No. 3,868,319), and comprises apparatus for extending the principles there taught to the general field of environmental protection.
It makes use of a known material which has the property of being preferentially absorptive of oil in the presence of water, on which the material floats. This material is fully described in U.S. Pat. No. 3,630,891, which also teaches using the material in the form of a blanket to be deposited on contaminated surfaces and allowed to absorb the contaminant.
My copending application referred to above teaches the use of the material not in blanket but in small pads or scraps, positioned and retained in the recirculation path of water for swimming or other artificial pools. In this limited application the material functions admirably, and the method has found ready commercial acceptance.